超音波參數聲學陣列可以發出高度指向性的聲束，以調幅或調頻技術將音樂信號加載在超音波上，透過聲波在空氣介質傳播的非線性效應，可以自動解調音樂信號，產生可聽聲音， 這種現象也稱為自解調(Self-modulation)。 在這項研究中，我們以調幅及脈波寬度調變技術調變200kHz載波，D類全橋電晶體放大器驅動14個200kHz超音波換能器所形成的陣列。為增進線性度與切換抑制切換雜訊，我們採用平方根補償電路與帶通sigma-delta調變電路，儘管該研究的改進和進步還有很大的餘地，但它對參數陣列提供了很好的初步了解，並提供了一種用於分析和測量聲音線性度的工具。

The parametric acoustic array has been achieved the highly directional sound beam, which have resulted from the study of nonlinear Acoustics, it use of sum and difference frequencies in air which are due to the effect of air nonlinearity to produce audible sound. This phenomenon is also called self-demodulation. In this research, we construct the fourteen 200 kHz ultrasonic transducers to make an audio spotlight, the square root amplitude modulation circuit was combined with the modulation of the band-pass sigma-delta to produce a basic parametric array. Although there is still a lot of scope for the improvement and advancement of this research, it effectively takes a good preliminary look at the parametric array and offers a circuit for analyzing and measuring of tones occurring from nonlinearity of the air.

Thesis Validation Letter
Acknowledgements
摘要
Abstract iv
Table of Contents
Table of Figures
Table of Tables
Chapter 1 Introduction
1.1 Research Background and Motivation
1.2 Thesis Organization
Chapter 2 Overview of Parametric Acoustic Array in the Air
2.1. Theoretical Structure of the Parametric Acoustic Array
2.2. Realization of Parametric Loudspeakers
2.3. Signal Transmission and Modulation Techniques
2.3.1. Double-Sideband Amplitude Modulation
2.3.2. Square-Root Amplitude Modulation
2.3.3. Single-Sideband Amplitude Modulation
2.3.4. Modified Amplitude Modulation
Chapter 3 Design and Implementation
3.1. Ultrasonic Transducer
3.2. Power Driver for Parametric Acoustic Array
3.2.1 Square Root Amplitude Modulation Circuit Design
3.2.2 Band-pass Sigma-delta Modulation Circuit Design
3.2.3 Non-overlapping Circuit Design
3.2.4 Class-D Amplifier Design
Chapter 4 Analysis and Experimental Results
4.1 SRAM Measurement Result
4.2 BPSDM Measurement Result
4.3 Non-overlapping Circuit Measurement
4.4 Class-D Amplifier Test Result
4.5 Demodulated Signal and THD Measurement Result
Chapter 5 Conclusion and Future Work
5.1 Conclusion
5.2 Future Work
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